Double-throw clamping switch



APril 3, 1951 A. s. cAswr-:LL 2,547,153

DOUBLE THROW CLAMPING SWITCH Filed Aug. 21.71946 3 Sheets-Sheet 1 1 2 E2l Q lllllllll] 1o 15 ,f '--Ld 12e 17 14 11S- l 5 Hl 1y "Q'lf-l \O 6 l AI' 1 e3 F1o. 1d

^ l A INVENTOR.

F13. 1 ApfhUpSCdsM/ell ATToRN/ys April 3, 1951 A. s. cAswELl. 2,547,153

DOUBLE THROW CLAMPING SWITCH Filed Aug. 21, 1946 3 Sheets-Sheet 2INVENTOR.

BY Arrhurv 5.Cc1sweH mxya ATTORNEYS f April 3, 1951 A. s. cAswELl.

DOUBLE THROW CLAMPING swITcH s-Sheet 3 3 Sheet Filed Aug. 2l, 1946 e f 95 9 l 9 7. 6 m 7 J www m w N Ns WR Ed 0 V T. NC T [3 A. n..

.Screw member threaded at both ends. i switch isa-two-blade single poleswitch and isV so arranged that when the contact is moved into @either'of its Ycontact engaging positions, it is -hlam'pe'd-against thestationary-contact mem- *bers When the contact member is in one of itsmember.

Patented Apr. 3, 1951` Arthur S.'Caswell,` Philadelphia, Pa., assignorto I. T. E. Circuit Breaker Company, Philadelphia, Pa., a corporationof'iPennsylvania Application August 21, 1946, Serial No. 691,927

1 Claim. (Cl. ZOO- 170) My present invention relates to switchgear and gmore particularly to double throw switchgear .arranged to engage themovable'contact with the stationary contacts in a tight clampingarrange- Vment in ,each position of the double throw switch. lHeretofore in switchgear of the knife switch type, it has been customaryto provide a clamping arrangement for interengaging the movable elementof the knife switch with the stationary contact. A portion of theclosing movement of;

the switch was used to bring the movable contact or blade up intoregistry with the stationary Contact andthe remaining movement of theswitch handle performed the clamping action.

vThis type of clamping action is shown in theI Scott Patent 2,246,072,assigned to the assignee yof the present invention.

However, the problem becomes more complex in double throw switches wherethe movable contact blade has a neutral position as well as two separatecontacting positions-180 apart."

Various means have been attempted to'l provide for adequate clampingpressure at both contact- -ing positions of the knife .blade but'thesehave resulted either in extremely complex duplicatev clamping mechanismsor in having a clamped contact arrangement at one position only with theother position being subjected toonly light clamping engagement.

-In general, my invention contemplates the utilization of a single righthand thread screw member which will be actuated when the switch isclosed in either direction to clamp the switch blades tightly across thecontacts, although` it will `be understood that a left handed screwmaybe employed, if desired.

`More specifically, my linvention contemplates a clamp tight switcharrangement in which the movable contact carrying arm is mounted on aThe contact engaging positions, the screw member is rotated clockwise.Clockwise rotation causes *the screw to react on a nut at one end as atthe left end through the nut to compress the contact member-against thestationary contact, the direction ofv the-clamping force being oppositeto the direction of axial movement ofv the screw The same clockwiserotation of the screw member, causes the other'end of the screw todirectly compress the movable Vcontact against the opposite side of thefixed contact, the force being-finfthe same direction as the axialmove-- ment of the screw member.

, opposite pole, counterclockwise.

description and drawings in which When the movable contact is moved toits the screw member is rotated the screw member causes the screw torotate on the nut located" on the opposite side from the above describednut, namely, on the right hand and thrcughthis other nut to compress themovable contact against the fixed contact inga'direction opposite to theaxial movement of the screw member. The same counterclockwise rotationcauses the other end of the screw member to directly compress themovable contact against the xed contact into the same direction as theaxial movement screw member.

summarizing the above, a screw member arrangement is thus provided whichclamps a movable contact against one of its two pole terminals when themovable contact is moved clockwise and clamps it against the other ofits two pole terminals when the movable contact is moved intooppositecounterclockwise direction. Accordingly a primary object of mypresent invention is to provide a simple clamping mechanism primarilyfor a double throw knife type switch wherein a single clamping memberand single operating means therefor is eiective to create proper contactengaging clamping pressure at both contact closing positions of theknife switch. Y

Another object of the present invention is the provision of clampingmeans for a double throw knife type switch wherein the clamping means isreleased when the switchblade is in neutral intermediate position butwherein the clamp is operated to engaged position on movement of theswitch handle in either direction from the neutral.

Another andimportant object of my invention is the construction'andarrangement of the operating mechanism so that the movable contacts willbeA clamped only when engaged with the 'Y stationary contacts.

A further object of my invention is the arrangement of the operatingmechanism of my switch to ensure appropriate sequential operation of thecontact and clamping mechanism to clamp the contacts in engagement onlyafter contact is fully made.

The foregoing and many other objects of my invention Will becomeapparent in the followin Figure 1l is aside view showing the generaloperation of my. novel clamping means for a double throw knife typeswitch.

Figure'la is a detail view of the handle locking mechanism of my novelswitch.

Figure 2 is a perspective view showing my novel switch in theupperconnected position vpartially broken away to show the operation ofthe clamping means and the double dog latch.

Counterclockwise rotation. of

.tionary contact I3. I3 are supplied with special contacting surfaces lsulating panel I I.

Figure 3 is a cross sectional view of the clamping mechanism 10 when theswitch is in the upper connected position.

Figure 4 is a view corresponding to that oi Figure 3 showing thearrangement of the clamping mechanism when the switch is open with the nswitch handle in the neutral position.

Figure 5 is a view corresponding to Figure 3 showing the arrangement ofthe clamping mechanism with the switch in the lower connected position.

Referring now to Figure 1, my novel doublethroW knife type switch ID ismounted on an insulating panel II which carries the upper stationarycontact terminal I2 and the lower sta- Contact terminals I2 and I4, I4and are connected to connection studs I5, I6 which pass throughappropriate openings I1, I8 in the insulating panel I I.

The movable contact assembly 25 is mounted on the central terminal block2e which in turn is conductively secured to the back connection stud 21which passes through opening 28 inv inpair of upper link members 30 andthe pair of l lower link members 3| pivotally secured thereto at pivots33 and 34, respectively. The opposite ends of the upper link members 30are pivotally secured by the rivets 35 to the clamp plate 15 hereinafterdescribed. The lower link members 3I are similarly pivotally secured bythe rivets 36 to the clamping plate 15.

My novel device is so arranged, as hereinafter described, that thecontact plates or blades 40 are bridged and clamped across centralterminal block 26 and Contact terminal I2 in the upper closed positionof the switch, and across terminal 26 and contact terminal I3 in thelower closedV position of the switch; but that in any intermediateposition, the plates or blades 40 will be spaced apart sufficiently sothat they may readily move from one contact bridging position to theother. Y

In operation, when the switch is in the up position of Figure 2, theinitial downward movement of handle 4I will release the clamp whichholds the contact plates 40 tightly against the stationary contact I2and terminal 26. Subsequent downward movement of handle 4I will move thecontact plates 40 down to the neutral position shown in Figure l. Stillfurther downward 'Y movement of handle 4I will bring the contact plates4G into registry with the lower stationaryl contact I3 and terminal 26.The iinal downward Terminal block 26 carries the movement of handle 4Iwill clamp the contact plates 40 tightly against the lower contact I3and the terminal 26.

The entire clamping action is accomplished by a single clamping screwhereinafter described ,which screw will effect the clamping operationwhen it is turned clockwise with respect to Figure 2 when the switchhandle 4I is raised; and counterclockwise with respect to Figure 2 asthe switch handle 4I is lowered to the clown position.

The switch handle 4I is, as shown in Figure 2,

secured in any suitable manner to the bracket 43,

which bracket 43 is mounted for limited rotation Y on the pin 45 carriedbetween the side members 46, 41 of the handle assembly.

Latches 50 and 5I as shown in Figures 1 and 1a, are also rotatably,mountedv on pin 45 and are each provided with latch tip elements 52, 53respectively and dog leg portions 54, 55 respectively.

Dog leg portions 54, 55 of latches 5U and 5I extend up on either side ofpin which is carried between the plates of bracket 43.

When the handle 4I and the entire movable contact assembly 25 are raisedto the upper contacting position, latch tip 52 of latch 5U engages thekeeper 62 at the top of stationary contact element I2. Similarly whenthe handle 4l and the movable assembly 25 are in the lower position,latch tip 53 of latch 5I engages the keeper 63 on the lower stationaryContact I3. These latches thus prevent the handle assembly, includingthe movable Contact, from dropping down or being physically shocked outof engaged position and thus actually relieving the clamping pressure onthe contact blades 46. These latches also. prevent the blade from beingblown off in casevof excessively high current. Y

When, however, with the elements shownjn Figure 2, handle 4I is pulleddown, handle member 43 bears against dog leg 540i latchj .and rotateslatch 5D clockwise to disengage latch tip 52 from keeper 62. Furtherdownward movement of handle 4I brings the projection 65 of the latch 50against the stop pin 6G to prevent further movement of handle member 4Iand handle member 43 around the pin 45 so that the entire contactassembly now rotates about the pivots 53 and 34 to move down.

Similarly, when the lower contact I3 is engaged, a lift of handle 4Iwill first cause pin 6U to engage dog leg 55 of latch 5I to disengagelatch tip 53 from keeper ES and subsequent lifting of handle 4I causeslatch 5i to bear 'against the opposite side of member 65 so that furtherlifting of handle 4I causesthe contact assembly torotate upwardly aroundpivots 33 and 34. This movement of the entire contact assembly 25.aroundpivots 33 and 34 is in addition to the movement of the plates 46, 41around the center of clamp operating screw 10 hereinafter described.

When the contact assembly 25 is in the neutral central position shown byFigure l, projection66 is pressed by the compression spring 61 into thenotch 12 of the central extension 13 of the terminal 26, mounted on thefront of panel l I and thus maintains the entire movable contact 25 inneutral position. k

In order to rotate the movable contact assembly 25 to the upperconnected position of Figure l the handle 4I is first pulled to theright with respect to Figure l. i Thisk compresses the spring 6l andremoves the projection 66 from the center- Ving notch 12 in the centralextension 13 and permits the entire contact assembly 225 to be rotatedaround the pivots 33 and 34 until the contact blades 40-45 are inengagement with the upper stationary contact terminal I2 and the centralcontact terminal block 26. At this point further upward motion of thehandle 4I will rotate the operating handle assembly 44 in acounter-clockwise direction, with respect to Figures tl and 2, to causethe contact blades 40 to be clamped tightly against the upper andcentral terminals as hereinafter described. Y

The same action occurs, of course, during downward movement of thecontact assembly 25 toward I3. r

Thus the movable contact assembly 25 when it is in any of the threepositions above set forth actually has three centers of rotation. Firstthe handle 4I and its bracket 43 rotates about pin 45 to disengageeither the latch 5G or 5I depending on whether Contact is made at thetop or bottom. Second, the contact assembly is then rotated to its nextposition about the centers 33 and 34.

flfhirdly, after yeither contacts |2.or i3 have been engaged, the handleassembly rotates-about the screw l to clamp the contact blades el)against :either of the stationary contacts I2 or i3 .and terminal 2'6.

The iirst and second centersv of rotation (pin 45, and pivots 33 and 34)have already been described both as to'characteristics and operations.

The operation of the third center of rotation (about screw 1l!) in orderto clamp the .movable Contact blades 45 against either of the stationarycontacts is shown more specically in connection with Figures 3, 4 and 5.

Each of the pair of movable contact blades 4Q and 40' is provided with aclamping plate 15, 15'. The clamping nuts 16 and 15" bear against theclamping pates 15 and 15 in orderto exert pres s'ureonthe blades 4d and4G. The clamp-ing nuts 16 and 16 are adjusted and locked by set screws18, 18' registering and engaging some of the '-notches 19, 19 of each ofthe nuts 15, 16'; the set screws being threaded into appropriatefthreaded openings in the clamping plates 15, 15'.

It should first be pointed out that the clamp- -v ing screw 1li is aright hand threaded screw and that this single screw is utilized toperform the clamping function at both the top and bottom position. Theadvantage or this type of construction lies in the fact that right handthreads are standard practice in the manufacture of 'screws and thuseliminates the necessity for a special machining operation .requiringcomposite threading; and also the arrangement shown in Figures 3, 4 and5 is such that for the iirst time a clamping action .is accomplished byrotating 4,an ordinary right-hand clamping `screw in either 'a'clockwise or.y counterclockwise direction. It will be understood,however, that a left-handed screw may be used or a double threaded screwat vopposite ends may be employed for direct action in place of thereaction on the nut.

The handle assembly 4A is keyed to the clamp- .ing screw 1!) through therectangular recess 1I. Clamping-screw 1e is a substantially cylindricalmember as shown having a squared portion 1Go. .Handle assembly lll isprovided with a matching .rectangular recess 1l receiving the squaredportion c of the member 1e. Clamping'screw 10 is provided with thethreaded end 19a engaging the threads of nur te and the threaded end webf engaging the threads of nut 1S.

When the movable contact assembly 25, in- 'cluding the operating handleassembly 44 has moved'the blades all and 6.16 to the upper contactingposition, the blades et, All and the clamping plates 15, can no longermove counterc'ock'- wise. Thereafter further lifting of the handle 4|rotates the screw 1li in a counterclockwise direction, with respect toFigure 1.

This rotation about the center of the screw 1t -occursafter the entireassembly has been rotated around the pivots 3S and 34 to the upperbridging position. This rotation now unwinds the threaded end 1Gb ofclamping1 screw 1U from the right-hand clamping nut 16', and turns the fthreaded end ma into 16, Figure 3. i

Since the clamping nuts 'I6-and 16 are prevented from rotating by theset screws 18,718 the further rotation of the operating handle 44 drawsthe face 11 of the clamping nut 15 against the clamping plate 15 and theannular shoulder 91 fof the screw 10 against the right hand clampingjwasher 495 forcing the washer against the right the-/left-hand clampingnut 'h'and clamping plate 15.

Y In this position the corresponding lefthand clamping washer in recess9E of left-hand end of the screw 19 is loose.y

Thus, the further rotation of screw 10 above described will draw theclamping plates 15, 15' together to exert clamping pressure on blades40, 4U and drive the blades into tight clamping engagement with contactsi 2 and 26.

This pressure is obtained as shown by clamping nut 16 rmly engagingclamping plate 15 and by clamping washer 95 iirmly engaging clampingplate 15.

The reverse or opposite action of the above procedure takes place whenthe handle assembly is moved downwardly as shown in Figure 5. Here thescrew 1! is turned clockwise with respect to Figure 1 and draws theright-hand clamping nut 76 against the right-hand clamping plate 15' andthe' left-hand clamping washer 95 against the left-hand clamping plate15, thereby exerting The entire assembly is released and returns toneutral position as shown in Figure 4 on movement of the switchingmembers from the position of Figure 3 or the position of Figure 5 (theup or down positions) toward the central or neutral position. v

By means of the foregoing it will thus be seen that a single memberhaving ordinary simply machined right-hand threads at each end mayreadily be used to provide an effective clamp for a double throw knifeblade type switch wherein the bridging or connecting blades areeffectively clamped at both the upper and lower positions.

In constructions heretoforeproposed, the mechanism corresponding tohandle assembly 25 is so arranged in relation tothe clamp tighteningscrew lil, the clamps 15 and the contact blades 40 that should theoperator be careless, it may be possible for him to rotate the handleassembly with respect to contact blades 5B and clamps 15 to tighten theclamps before the blades are across the contacts i2 and 2B or contactsi3 and 2li.

A skilled operator may, however', loe relied on to hold the handleassembly 25 horizontally while raising the contacts to the upperbridging condition or lowering them to the lower bridging condition.However, should an unskilled operator undertake to operate my novelswitch, he may accidentally rotate the handle assembly 25 with respectto the contact bladesiilll and clamps 15 before the contacts areengaged; cr when the con# tacts are engaged, for instance, in the upposition, he may V'pull the handle down through its complete rotationabout the center of screw le to reclamp the blades across the up contactposition without removing the blades .from itsrup contact position.

Accordingly, my invention provides for a double dog latch `lili! whichis secured to the contact assembly. The upper end of the double doglatch IBB has an extension le! secured to the tension spring 402 whichin turn is secured to the rivet 35 carried by the clamping plates 15,15'.v The lower end of double dog latch -l also has an extension IMconnected to the tension spring 05 which in turn is connected to therivet 36.

The tension springs EQ2- tile maintain the Adouble dog latch Ille in aposition substantially Vto rotate outwardly or clockwise.

||2 carrying the latch roller H3 between them.

The double dog latch |09 is provided with recesses H5 and H6 receivingrespectively the rollers and ||3. The handle assembly 44 is providedwith the pin 22 which supports the latch roller |22 in the centralrecess |2| of the double dog latch |09 when the movable contact assembly25 is not in either the upper or lower connected positions. In the openhorizontal position of the switch, the roller |22 or handle assembly 44is held in the latch recess |21. As the handle assembly 44 is raised tobridge the blades 40 across contacts l2 and 25, the engagement of roller|22 in latch recess 2l prevents handle assembly 44 from rotating withrespect to blades 40'and clamps 15. Consequently the entire assemblyrotates on the pivots of links and. 3 i.

When the upper position is reached, the upper end |25 of double doglatch |92 strikes against adjusting pin |25:` of the upper contact l2and further lifting movement of handle assembly 44 causes the upper end|25 or" double dog latch |82 By this time contact blades 49 are acrosscontacts l2 and 26 but unclamped. As the double dog latch |94.) isrotated outwardly clockwise by adjusting pin |25 engaging its end E25 asabove described, the latch recess |2l is disengaged from latch roller|22 of handle assembly 44 and the handle assembly 44 may now rotateabout the center of screw 10 to the position where latch roller |22 Willreach the location shown in Figure 2.

At this time, therefore, handle assembly 44 rotates about the center ofscrew i9 with respect to vthe Vcontact blades 49 and clamps 75 thusclamping the contact blades 49 across contacts I2 and 2B as abovedescribed.

When the switch is opened, handle assembly 44 is irst unlatched aspreviously described, and then rotated downwardly or in a clockwisedirection. As it rotates downwardly, it rotates about the center ofscrew 'l thus unclamping the blades 40.

When the unclamped position is reached, latch roller |22 has moved fromthe location of Figure 2 into the latch recess |2|. Thereafter furtherpulling down of handle assembly 44 pulls the contact 40 out from acrosscontacts' |2 and 26 and the rotation of the entire moveable contactassembly 25 is controlled by' links 30 and 3|. Thus the handle iscontrolled so that it cannot clamp the Contact blades together untilafter the contact blades are across the terminals.

During the opening operation after the contact blades are unclamped,further movement of .the handle assembly toward neutral position must`be followed by movement of the contact blades toward neutral positionowing to the engagement of roller |22 in latch recess l2i. Accordinglythe'clamp cannot be operated until after the bridging contacts have beenengaged across the terminals and also the clamp cannot be operatedfalsely by a complete rotation of handle assembly 44 to reclamp acrossthe same terminals. The motion which opens the clamp must necessarily befollowed by movement of the switch blades toward neutral position.

Similarly when the contact blades 4@ and clamps 75 are moved to aposition where they bridge terminals I3 and 25 in the down closedposition of the switch, end |30 of double dog latch |00 first strikesadjusting pin ll on the lower `terminal I3. This occurs just after thecontact blades 4E! have moved to a position bridging terminals 26 andI3.

When the lower end |30 of double dog latch is thus moved out, latchroller |22 is then released from the latching recess 12| so that thehandle assembly 44 may then be moved down to clamp. Similarly duringopening from the bottom closed position toward neutral, the handleassembly 44 first rotates about the center of screw 'lo to release theclamping engagement or the switch blades across the lower contactposition and then the roller |22 engages in recess- |21 so that furtherlifting of handle assembly 44 moves the switch blades from the lowercontacting position back toward neutral.

By this means therefore, the clamping operation is made fool-proof andthe switch may be operated to the up or down position and will not beclamped until after theA contacts have been engaged and will also not beaccidentallyv reclamped across the same set of contacts whentheintention is to open the contacts.

Thus, even an unskilled operator may operate the switch of my inventionmoving-the switch blades across the contacts and thus clamping them inthe appropriate sequence or unclamping the switch blades and removingthem from across the contacts also in proper sequence.

In the .foregoing I have described my invention solely in connectionwith a specic preferred embodiment thereof. .Since many variations andmodications of my invention should now be obvious to those skilled inthe art, I prefer to be bound not by the specific disclosure hereincontained, but only by the appended claim.

I claim:

A double throw switch comprising a rst contact, a second contact, aswitch blade carrying a contact and having a neutral position andmovable in one direction to engage said rst contact and in the oppositedirection 'to engage said second contact, a screw clamp memberarrangement carried on and rotated by said blade to clamp said switchblade contact against said iirst contact when the movable contact ismoved clockwise and clamp it against said second contact when themovable contact is moved into oppositeV counterclockwise direction, adouble dog Vlatch secured to and operable with said blade,

spring means for maintaining said latch substantially parallel to saidswitch blade in its movement, said latch preventing rotation of saidscrew member until contact engagement between said switch arm and rst orsecond contact occurs, and means automatically operative when contactenga-gement is eected for moving said double dog latch to permitrotation of said screw by said blade for eilecting clamping engagement.

ARTHUR S. CASWELL;

REFERENCES CITED The following references are of record in the file ofthis patent:

UNITED STATES PATENTS Number Name Date 473,134 Soden Apr. 19, 1892488,740 Pattison Dec, 27,1892 528,900 Bolles Nov. 6, 1894 633,771 Wrightet al. Sept. 26, 1899 1,213,960 Sessions Jan. 30, 1917 1,850,771 RaneyMar. 22, 1932 1,929,049 Austin Oct. 3, 1933 2,214,180 Reynolds Sept. 10,1940 2,246,072 Scott, Jr June 17, 1941 2,288,134 Hoye June l130, 1942

